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Hell everyone! I'm new to Mustang Forums, I just got a 2011 5.0 with the Shaker 500 system. After researching for what feels like weeks now I'm trying to figure out the absolute BEST way to install an aftermarket subwoofer and amplifier. There are so many posts on forums all over the net that suggest certain ways of doing it, then other people chime in and say no this isn't the best way... and on and on and on.

Originally what I read was the easiest and best way to go about doing this was to get a PAC SNI35 LOC and tap into the connector on the back of the radio that has AUX + and AUX - for signal to convert into rca's. I ordered one, wired everything as suggested and my subwoofer makes no noise. The amp turns on, everything looks like it should work but nothing. I'm thinking that the wires I tapped into for signal probably aren't the optimal wires.

I've seen all over the internet people tapping into the rear speaker signals for their LOC and saying it sounds great, then other people say you shouldn't do that because the rear speakers lose bass frequencies at higher volumes. Others say an AudioControl LC2I 2-Channel LOC prevents this... I'm lost!

Long story short, I need to know the BEST method to get the highest possible quality signal to my aftermarket amplifier, while keeping the factory head unit. I don't want to lose bass from my subwoofer at higher volumes! I want to be able to blast it and have nice crisp clear sound in my new Mustang! Help! Thanks

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IMHO you can't get "the best possible sound" from a stock head unit. If you want the best possible sound you will have to go aftermarket. Now that I have said that I think way to get the best sub sound for your current setup is to get the sub input from the wires coming out of the back of the radio going to the front speakers. I don't know how the rear speakers are tuned from the factory, but like you I have heard that they aren't optimal for wiring a sub. I did use them on my last car for a short period of time to hook up an amp for all 4 speakers before I got my system fully installed, and I didn't notice anything wrong with the way they sounded so it might be an option.

Hell everyone! I'm new to Mustang Forums, I just got a 2011 5.0 with the Shaker 500 system. After researching for what feels like weeks now I'm trying to figure out the absolute BEST way to install an aftermarket subwoofer and amplifier.

you could use a LOC from one pair of the speaker output wires from the subwoofer amp in the kickpanel. The signal is already low-passed for the door subwoofers.

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Originally what I read was the easiest and best way to go about doing this was to get a PAC SNI35 LOC and tap into the connector on the back of the radio that has AUX + and AUX - for signal to convert into rca's. I ordered one, wired everything as suggested and my subwoofer makes no noise. The amp turns on, everything looks like it should work but nothing. I'm thinking that the wires I tapped into for signal probably aren't the optimal wires.

it depends. if you're tapping into the AUX1 wires that are already there for the door subwoofers, then the signal level is too low to use a LOC. that is an un-amplified signal which is about 250 mV RMS max, plus it's a balanced output so you can't run it straight to an external amp. if you're trying to use the AUX2 pins (the empty 4 pins in that connector) those aren't turned on. They're only used if you have the Shaker 1000.

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I've seen all over the internet people tapping into the rear speaker signals for their LOC and saying it sounds great, then other people say you shouldn't do that because the rear speakers lose bass frequencies at higher volumes. Others say an AudioControl LC2I 2-Channel LOC prevents this... I'm lost!

there is a minor bass "cut" above volume step 28 but that applies to all output channels, not just the rear speakers. If you're adding a subwoofer to what you already have I doubt you'll notice this much if at all.

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Long story short, I need to know the BEST method to get the highest possible quality signal to my aftermarket amplifier, while keeping the factory head unit.

it doesn't really matter so long as the signal level is high enough to keep the S/N ratio high.

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Originally Posted by ticopowell

IMHO you can't get "the best possible sound" from a stock head unit. If you want the best possible sound you will have to go aftermarket.

this is BS. There's no difference in absolute quality between a factory and an aftermarket HU; both OE and aftermarket build them from the same off-the-shelf parts. Yes, I've tested and cracked open enough of them to say this with certainty.

What happens is people swap in an aftermarket HU and notice how different it sounds, which is because the aftermarket HU has no EQ. Then they assume it must be "better" because it's aftermarket; any I've listened to are screechy, annoyingly fatiguing messes.

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I don't know how the rear speakers are tuned from the factory, but like you I have heard that they aren't optimal for wiring a sub.

the only possible difference is that the rear speakers might have a higher crossover point, but then you just compensate by turning up the level on the subwoofer amp.

this is BS. There's no difference in absolute quality between a factory and an aftermarket HU; both OE and aftermarket build them from the same off-the-shelf parts. Yes, I've tested and cracked open enough of them to say this with certainty.

What happens is people swap in an aftermarket HU and notice how different it sounds, which is because the aftermarket HU has no EQ. Then they assume it must be "better" because it's aftermarket; any I've listened to are screechy, annoyingly fatiguing messes.

This stuff isn't magic, folks.

I'm not saying I am an expert, nor have I torn them apart, so all of the following is IMHO, and it is all from hands on experience with setting up HU's in mustangs. I know most of the electronics are the same, but you do have EQ control on aftermarket from my experience. all of my HU's have had a multi-freq EQ control. Also I have yet to see a stock EQ control that has more than bass, mid, and treble controls. If you want really high control you can get a dedicated eq controller.
I don't know what radios you are listening too that sound screechy and annoyingly fatiguing, but if installed right, and tuned correctly(some have an auto-tuning capability) they can sound a lot better, with or without aftermarket speakers. I have seen improvements with both just speakers installed, and on the other hand I have seen improvements with just a HU installed.
Yeah it isn't rocket science, but it can be confusing to newcomers to car audio.

I'm not saying I am an expert, nor have I torn them apart, so all of the following is IMHO, and it is all from hands on experience with setting up HU's in mustangs. I know most of the electronics are the same, but you do have EQ control on aftermarket from my experience.

yes, and what EQ capability they give you is pathetic. The $600 Alpine 2-DIN touchscreen I just put in my Ranger has a 7-band EQ which is basically a graphic EQ with slightly adjustable center frequency and Q. The OE radios have 7 bands of EQ per channel which are fully parametric, and can be boost/cut, highpass/lowpass, shelving, allpass, notch, whatever kind of second-order filter possible.

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all of my HU's have had a multi-freq EQ control. Also I have yet to see a stock EQ control that has more than bass, mid, and treble controls.

The EQ capability is there, it's just not exposed to the end user. With good reason, most people wouldn't have a clue what to do with it.

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If you want really high control you can get a dedicated eq controller.

Yes, I know. I paired that $600 Alpine head unit I mentioned with a MiniDSP. the Alpine's built-in EQ capability was only enough to make the sound tolerable.

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I don't know what radios you are listening too that sound screechy and annoyingly fatiguing, but if installed right, and tuned correctly(some have an auto-tuning capability) they can sound a lot better, with or without aftermarket speakers.

It isn't the radio which "sounds screechy." See, the thing is, when you EQ a system, 90% of what you're doing is correcting for the vehicle cabin and the installation of the speakers. Basically you can have the best speaker in the world and it'll sound like crap once you install it into a car. the dimensions of the interior dictate what frequencies you'll have problems with, but typically you end up with cancellations around 125, 250, and 500 Hz. When you put a speaker in the door, you usually get a large "hump" in the midrange somewhere between 800 and 1200 Hz depending on the thickness of the door. And the grilles are usually good for making anything between 3 kHz and 6 kHz peaky as hell.

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Originally Posted by ticopowell View Post
IMHO you can't get "the best possible sound" from a stock head unit. If you want the best possible sound you will have to go aftermarket.

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this is BS. There's no difference in absolute quality between a factory and an aftermarket HU; both OE and aftermarket build them from the same off-the-shelf parts. Yes, I've tested and cracked open enough of them to say this with certainty.

Most of the distortion in a head or amp comes from the output stages. Tapping into the speaker level signals to go into an amp is a workaround, you are amplifying all of the distortion from the head output stages, or worse-the external factory amp. Aftermarket heads that have line level outputs (everything else being equal) skips all of the distortion of the factory output stages and will typically give you a cleaner sound with less distortion. I stuck with the factory head to keep the *****-mine is easy to adjust while driving, and I'm only amping the door subs. If I wanted to amp up the other speakers I'd prob go aftermarket.

"I never try to dissuade a man from trying an experiment. If he does not find what he wants he may find something else."
James Maxwell

Most of the distortion in a head or amp comes from the output stages. Tapping into the speaker level signals to go into an amp is a workaround, you are amplifying all of the distortion from the head output stages, or worse-the external factory amp.

any radio or amplifier which isn't in clipping and yet has audible distortion is broken and should be tossed in the garbage. besides, we usually discuss distortion as a ratio, so even if there was distortion there to amplify you're also amplifying the fundamental signal by the same amount. So the ratio stays the same. the attached measurements are from an OE radio; the output waveform is as close to a perfect sinewave as you can expect. 0.06% THD+N is close enough to zero to say there's no distortion there for a downstream amplifier to boost. And the 2nd harmonic is almost 70 dB down from the fundamental.

Most amps take their THD readings at 1Khz, like you show, at a low level, because the numbers look very good at that point. Sometimes a resistive load is used not a speaker which helps the data look better. I'd like to see the same data at 10KHz and 35 Hz at 70% of full volume. I'd like to see the data when the amp is run into a speaker level to line level convertor. The impedance mismatch will often hurt the sound as well.
Btw, most 8 bit scopes are about 3dB or 15% accuracy, and many interpolate the data...by taking 2 or 3 data points and turn it into a sign wave. I can do the same measurement to show a PWM signal look as good as your data.
There are other distortion factors such as delays. If all amps are driven from the same source, they should be in sync across their entire freq bandwidth. If an extra amp is added-it adds a slight delay which some people can hear, especially at higher frequencies. That's just a few reasons why many aftermarket systems run everything from the line level outputs. I'm not sure why Ford elected to make their our standard for the signal levels and not use Line outputs, it would make it much easier to add amps and upgrade speakers.

Most amps take their THD readings at 1Khz, like you show, at a low level, because the numbers look very good at that point. Sometimes a resistive load is used not a speaker which helps the data look better.

the only way that would make a difference is if the amp's output impedance is too high. the output impedance of a typical solid-state amplifier is 0.1 ohms, so it doesn't really matter.

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I'd like to see the same data at 10KHz and 35 Hz at 70% of full volume.

if you had looked at the wave form, you'd have seen that this was at about 7 volts RMS output, which is only -1.2 dBV from full output (most non-boosted head units can put out 8 volts RMS clean from all four channels simultaneously.) So I was already well above 70%.
and worrying about distortion at 10 kHz is silly; the 2nd harmonic produced by any distortion there would be at 20 kHz and if you're an adult the chances of you being able to hear anything at 20 kHz is slim.

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Btw, most 8 bit scopes are about 3dB or 15% accuracy, and many interpolate the data...by taking 2 or 3 data points and turn it into a sign wave. I can do the same measurement to show a PWM signal look as good as your data.

these were taken using an Audio Precision APx586, which is hardly an "8 bit scope."

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I'm not sure why Ford elected to make their our standard for the signal levels and not use Line outputs, it would make it much easier to add amps and upgrade speakers.

balanced (differential) outputs have superior common-mode noise rejection than unbalanced (single-ended.) which means you don't have to worry too much about not running your audio wires near any other circuits; any noise picked up by the audio wires will be nearly the same on both (+) and (-) and will cancel out at the receiving end.

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